Immediately, both felt a warmth spreading in their bodies. Heat rose as Jeff tried to check which vial he had drunken. In shock, he saw the label. It was the height vial. His eyes widened as he realized the he had just drunken the full vial, more then 4 times the amount he had earlier used. His heart dropped as checked on the vial Mary used on herself. He already knew, that this must be the muscle vial, but froze as he noticed that the vial was also completely empty. This was also a lot more then he used on himself but it must be a hundred of times more then Mary got from his sperm. Jeff could not imagine what a full dose would possible do to her already powerful muscles. Only a few drops had turned her in the strongest and most powerful being on earth.
"Are you crazy", he cried as Mary violently began to shake. Once more, her tentacles began to pulsate as the as the growth took effect. Unwillingly Jeff got turned on by the thought of her already powerful girlfriend grow even stronger. His cock responded to his desire as it got rock hard. Mary lifted her octopus body up and placed herself on his waiting rod. She felt the strength rise inside her as her muscle grew bigger and denser. Her whole anatomical structure changed once again.
Jeff could not do anything else then fucking her hard. He also felt the growth taking effect as he slowly extended in all directions. He shot up to about 10 feet. His member still inside her ached from the lack of space as it grew.
Mary on the other hand enjoyed the felling as strength flooding her muscles like a waterfall. Her muscles hardened beyond any imagine. Indestructible. She shoot several tentacles right though the concrete wall of the pool into the ground trying to get some hold as she fucked Jeff hard again the pool wall. The tiles cracked with each super powerful thrust. Jeff grew another 5 feet as he began to sit on the pool ground. Mary was still sitting on his erect member as she got lifted out of the pool. She was able to contain only half of his length as he continued to grow.
The changes to Mary were only slightly visible as her upper torso got more defined and ripped and her appendages grew decent in size. But she knew that she must be ten times stronger then minutes ago. Both continued their growing maniac, Jeff shot up to 20 feet and Mary got stronger with each passing second.
Eventually, Jeff came inside her ejecting his sperm - and the growth serum - right into Mary. Mary could only contain one quarter of her boyfriends giant cock as she felt all her appendages to lengthen. Her upper body only grew only a little bit. The tentacles on the other hands stretched to almost 20 feet long. By the time, Jeff was so big that his feet touched the opposite pool walls while still sitting on the ground.
Forcing more of Jeff's giant cock inside her, Mary allowed herself to stretch even more. Her skin turned almost completely transparent as she looked more like a jellyfish then an octopus. Her the skin around Jeff's cock were barely a millimeter thick but yet far harder and stronger then Jeffs whole 20 feet body. If she would pull her vaginal muscles together she could easily crush him.
When Jeff hit about 30 feet, his growth came to an halt. Mary slowly lifted herself up until she was about the height of his face. Her tentacles must have stretched to 40 feet long and 4 inches wide. There were harder then anything known on earth. Mary gave him a gentle kiss on his giant mouth, which were almost the size of her whole head.
She grabbed his upper torso with one of her long tentacles transforming the rest of her body to her human from again. She looked stunning. She had well defined rock hard muscles perfectly sized for a female, long toned legs. Her pectoral muscles nicely lifted her breasts up. Her arms looked toned but not to big. But Jeff new that those arms could easily lift a jumbo jet. She must have grown some inches.
Mary looked deeply in his eyes as she whispered, "Love you honey."